This invention relates to an improved hand tapping device for cutting threads in the walls defining holes or openings in workpieces. The device may be used in cooperation with the spindle of a drilling machine to provide alignment of the tap with the opening being tapped.
In conventional hand tap wrenches, the spindle of a drilling machine is sometimes used to hold a male center which is brought into contact with a female opening on the tap wrench to align the tap with the hole within the workpiece. As the tap wrench is turned to effect the tapping operation, the tap wrench advances proportionately toward the opening being tapped.
As a result, the machine operator must continuously move the machine spindle downwardly to maintain pressure from the machine spindle on the tap wrench to assure continued alignment during the tapping operation. This requires the operator to turn the tap wrench with one hand and to lower the spindle with the other hand. Due to this cumbersome requirement, often the tap comes out of alignment causing a misaligned tap or a broken tap.